// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holders nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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package org.objectweb.asm.tree.analysis;

import java.util.List;
import org.objectweb.asm.Type;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.FieldInsnNode;
import org.objectweb.asm.tree.InvokeDynamicInsnNode;
import org.objectweb.asm.tree.MethodInsnNode;

/**
 * An extended {@link BasicInterpreter} that checks that bytecode instructions are correctly used.
 *
 * @author Eric Bruneton
 * @author Bing Ran
 */
public class BasicVerifier extends BasicInterpreter {

	/**
	 * Constructs a new {@link BasicVerifier} for the latest ASM API version. <i>Subclasses must not use this constructor</i>. Instead, they must use the {@link #BasicVerifier(int)} version.
	 */
	public BasicVerifier() {
		super(ASM7);
		if (getClass() != BasicVerifier.class) {
			throw new IllegalStateException();
		}
	}

	/**
	 * Constructs a new {@link BasicVerifier}.
	 *
	 * @param api
	 *          the ASM API version supported by this interpreter. Must be one of {@link org.objectweb.asm.Opcodes#ASM4}, {@link org.objectweb.asm.Opcodes#ASM5}, {@link org.objectweb.asm.Opcodes#ASM6} or {@link org.objectweb.asm.Opcodes#ASM7}.
	 */
	protected BasicVerifier(final int api) {
		super(api);
	}

	@Override
	public BasicValue copyOperation(final AbstractInsnNode insn, final BasicValue value) throws AnalyzerException {
		Value expected;
		switch (insn.getOpcode()) {
		case ILOAD:
		case ISTORE:
			expected = BasicValue.INT_VALUE;
			break;
		case FLOAD:
		case FSTORE:
			expected = BasicValue.FLOAT_VALUE;
			break;
		case LLOAD:
		case LSTORE:
			expected = BasicValue.LONG_VALUE;
			break;
		case DLOAD:
		case DSTORE:
			expected = BasicValue.DOUBLE_VALUE;
			break;
		case ALOAD:
			if (!value.isReference()) {
				throw new AnalyzerException(insn, null, "an object reference", value);
			}
			return value;
		case ASTORE:
			if (!value.isReference() && !BasicValue.RETURNADDRESS_VALUE.equals(value)) {
				throw new AnalyzerException(insn, null, "an object reference or a return address", value);
			}
			return value;
		default:
			return value;
		}
		if (!expected.equals(value)) {
			throw new AnalyzerException(insn, null, expected, value);
		}
		return value;
	}

	@Override
	public BasicValue unaryOperation(final AbstractInsnNode insn, final BasicValue value) throws AnalyzerException {
		BasicValue expected;
		switch (insn.getOpcode()) {
		case INEG:
		case IINC:
		case I2F:
		case I2L:
		case I2D:
		case I2B:
		case I2C:
		case I2S:
		case IFEQ:
		case IFNE:
		case IFLT:
		case IFGE:
		case IFGT:
		case IFLE:
		case TABLESWITCH:
		case LOOKUPSWITCH:
		case IRETURN:
		case NEWARRAY:
		case ANEWARRAY:
			expected = BasicValue.INT_VALUE;
			break;
		case FNEG:
		case F2I:
		case F2L:
		case F2D:
		case FRETURN:
			expected = BasicValue.FLOAT_VALUE;
			break;
		case LNEG:
		case L2I:
		case L2F:
		case L2D:
		case LRETURN:
			expected = BasicValue.LONG_VALUE;
			break;
		case DNEG:
		case D2I:
		case D2F:
		case D2L:
		case DRETURN:
			expected = BasicValue.DOUBLE_VALUE;
			break;
		case GETFIELD:
			expected = newValue(Type.getObjectType(((FieldInsnNode) insn).owner));
			break;
		case ARRAYLENGTH:
			if (!isArrayValue(value)) {
				throw new AnalyzerException(insn, null, "an array reference", value);
			}
			return super.unaryOperation(insn, value);
		case CHECKCAST:
		case ARETURN:
		case ATHROW:
		case INSTANCEOF:
		case MONITORENTER:
		case MONITOREXIT:
		case IFNULL:
		case IFNONNULL:
			if (!value.isReference()) {
				throw new AnalyzerException(insn, null, "an object reference", value);
			}
			return super.unaryOperation(insn, value);
		case PUTSTATIC:
			expected = newValue(Type.getType(((FieldInsnNode) insn).desc));
			break;
		default:
			throw new AssertionError();
		}
		if (!isSubTypeOf(value, expected)) {
			throw new AnalyzerException(insn, null, expected, value);
		}
		return super.unaryOperation(insn, value);
	}

	@Override
	public BasicValue binaryOperation(final AbstractInsnNode insn, final BasicValue value1, final BasicValue value2)
			throws AnalyzerException {
		BasicValue expected1;
		BasicValue expected2;
		switch (insn.getOpcode()) {
		case IALOAD:
			expected1 = newValue(Type.getType("[I"));
			expected2 = BasicValue.INT_VALUE;
			break;
		case BALOAD:
			if (isSubTypeOf(value1, newValue(Type.getType("[Z")))) {
				expected1 = newValue(Type.getType("[Z"));
			} else {
				expected1 = newValue(Type.getType("[B"));
			}
			expected2 = BasicValue.INT_VALUE;
			break;
		case CALOAD:
			expected1 = newValue(Type.getType("[C"));
			expected2 = BasicValue.INT_VALUE;
			break;
		case SALOAD:
			expected1 = newValue(Type.getType("[S"));
			expected2 = BasicValue.INT_VALUE;
			break;
		case LALOAD:
			expected1 = newValue(Type.getType("[J"));
			expected2 = BasicValue.INT_VALUE;
			break;
		case FALOAD:
			expected1 = newValue(Type.getType("[F"));
			expected2 = BasicValue.INT_VALUE;
			break;
		case DALOAD:
			expected1 = newValue(Type.getType("[D"));
			expected2 = BasicValue.INT_VALUE;
			break;
		case AALOAD:
			expected1 = newValue(Type.getType("[Ljava/lang/Object;"));
			expected2 = BasicValue.INT_VALUE;
			break;
		case IADD:
		case ISUB:
		case IMUL:
		case IDIV:
		case IREM:
		case ISHL:
		case ISHR:
		case IUSHR:
		case IAND:
		case IOR:
		case IXOR:
		case IF_ICMPEQ:
		case IF_ICMPNE:
		case IF_ICMPLT:
		case IF_ICMPGE:
		case IF_ICMPGT:
		case IF_ICMPLE:
			expected1 = BasicValue.INT_VALUE;
			expected2 = BasicValue.INT_VALUE;
			break;
		case FADD:
		case FSUB:
		case FMUL:
		case FDIV:
		case FREM:
		case FCMPL:
		case FCMPG:
			expected1 = BasicValue.FLOAT_VALUE;
			expected2 = BasicValue.FLOAT_VALUE;
			break;
		case LADD:
		case LSUB:
		case LMUL:
		case LDIV:
		case LREM:
		case LAND:
		case LOR:
		case LXOR:
		case LCMP:
			expected1 = BasicValue.LONG_VALUE;
			expected2 = BasicValue.LONG_VALUE;
			break;
		case LSHL:
		case LSHR:
		case LUSHR:
			expected1 = BasicValue.LONG_VALUE;
			expected2 = BasicValue.INT_VALUE;
			break;
		case DADD:
		case DSUB:
		case DMUL:
		case DDIV:
		case DREM:
		case DCMPL:
		case DCMPG:
			expected1 = BasicValue.DOUBLE_VALUE;
			expected2 = BasicValue.DOUBLE_VALUE;
			break;
		case IF_ACMPEQ:
		case IF_ACMPNE:
			expected1 = BasicValue.REFERENCE_VALUE;
			expected2 = BasicValue.REFERENCE_VALUE;
			break;
		case PUTFIELD:
			FieldInsnNode fieldInsn = (FieldInsnNode) insn;
			expected1 = newValue(Type.getObjectType(fieldInsn.owner));
			expected2 = newValue(Type.getType(fieldInsn.desc));
			break;
		default:
			throw new AssertionError();
		}
		if (!isSubTypeOf(value1, expected1)) {
			throw new AnalyzerException(insn, "First argument", expected1, value1);
		} else if (!isSubTypeOf(value2, expected2)) {
			throw new AnalyzerException(insn, "Second argument", expected2, value2);
		}
		if (insn.getOpcode() == AALOAD) {
			return getElementValue(value1);
		} else {
			return super.binaryOperation(insn, value1, value2);
		}
	}

	@Override
	public BasicValue ternaryOperation(final AbstractInsnNode insn, final BasicValue value1, final BasicValue value2,
			final BasicValue value3) throws AnalyzerException {
		BasicValue expected1;
		BasicValue expected3;
		switch (insn.getOpcode()) {
		case IASTORE:
			expected1 = newValue(Type.getType("[I"));
			expected3 = BasicValue.INT_VALUE;
			break;
		case BASTORE:
			if (isSubTypeOf(value1, newValue(Type.getType("[Z")))) {
				expected1 = newValue(Type.getType("[Z"));
			} else {
				expected1 = newValue(Type.getType("[B"));
			}
			expected3 = BasicValue.INT_VALUE;
			break;
		case CASTORE:
			expected1 = newValue(Type.getType("[C"));
			expected3 = BasicValue.INT_VALUE;
			break;
		case SASTORE:
			expected1 = newValue(Type.getType("[S"));
			expected3 = BasicValue.INT_VALUE;
			break;
		case LASTORE:
			expected1 = newValue(Type.getType("[J"));
			expected3 = BasicValue.LONG_VALUE;
			break;
		case FASTORE:
			expected1 = newValue(Type.getType("[F"));
			expected3 = BasicValue.FLOAT_VALUE;
			break;
		case DASTORE:
			expected1 = newValue(Type.getType("[D"));
			expected3 = BasicValue.DOUBLE_VALUE;
			break;
		case AASTORE:
			expected1 = value1;
			expected3 = BasicValue.REFERENCE_VALUE;
			break;
		default:
			throw new AssertionError();
		}
		if (!isSubTypeOf(value1, expected1)) {
			throw new AnalyzerException(insn, "First argument", "a " + expected1 + " array reference", value1);
		} else if (!BasicValue.INT_VALUE.equals(value2)) {
			throw new AnalyzerException(insn, "Second argument", BasicValue.INT_VALUE, value2);
		} else if (!isSubTypeOf(value3, expected3)) {
			throw new AnalyzerException(insn, "Third argument", expected3, value3);
		}
		return null;
	}

	@Override
	public BasicValue naryOperation(final AbstractInsnNode insn, final List<? extends BasicValue> values)
			throws AnalyzerException {
		int opcode = insn.getOpcode();
		if (opcode == MULTIANEWARRAY) {
			for (BasicValue value : values) {
				if (!BasicValue.INT_VALUE.equals(value)) {
					throw new AnalyzerException(insn, null, BasicValue.INT_VALUE, value);
				}
			}
		} else {
			int i = 0;
			int j = 0;
			if (opcode != INVOKESTATIC && opcode != INVOKEDYNAMIC) {
				Type owner = Type.getObjectType(((MethodInsnNode) insn).owner);
				if (!isSubTypeOf(values.get(i++), newValue(owner))) {
					throw new AnalyzerException(insn, "Method owner", newValue(owner), values.get(0));
				}
			}
			String methodDescriptor = (opcode == INVOKEDYNAMIC) ? ((InvokeDynamicInsnNode) insn).desc
					: ((MethodInsnNode) insn).desc;
			Type[] args = Type.getArgumentTypes(methodDescriptor);
			while (i < values.size()) {
				BasicValue expected = newValue(args[j++]);
				BasicValue actual = values.get(i++);
				if (!isSubTypeOf(actual, expected)) {
					throw new AnalyzerException(insn, "Argument " + j, expected, actual);
				}
			}
		}
		return super.naryOperation(insn, values);
	}

	@Override
	public void returnOperation(final AbstractInsnNode insn, final BasicValue value, final BasicValue expected)
			throws AnalyzerException {
		if (!isSubTypeOf(value, expected)) {
			throw new AnalyzerException(insn, "Incompatible return type", expected, value);
		}
	}

	/**
	 * Returns whether the given value corresponds to an array reference.
	 *
	 * @param value
	 *          a value.
	 * @return whether 'value' corresponds to an array reference.
	 */
	protected boolean isArrayValue(final BasicValue value) {
		return value.isReference();
	}

	/**
	 * Returns the value corresponding to the type of the elements of the given array reference value.
	 *
	 * @param objectArrayValue
	 *          a value corresponding to array of object (or array) references.
	 * @return the value corresponding to the type of the elements of 'objectArrayValue'.
	 * @throws AnalyzerException
	 *           if objectArrayValue does not correspond to an array type.
	 */
	protected BasicValue getElementValue(final BasicValue objectArrayValue) throws AnalyzerException {
		return BasicValue.REFERENCE_VALUE;
	}

	/**
	 * Returns whether the type corresponding to the first argument is a subtype of the type corresponding to the second argument.
	 *
	 * @param value
	 *          a value.
	 * @param expected
	 *          another value.
	 * @return whether the type corresponding to 'value' is a subtype of the type corresponding to 'expected'.
	 */
	protected boolean isSubTypeOf(final BasicValue value, final BasicValue expected) {
		return value.equals(expected);
	}
}
